The invention is in the field of energy-saving fluorescent lamp circuits.
Various ways have been devised for placing capacitors in series with fluorescent lamps to reduce the lamp current and thus save electrical energy. This reduces the light output, and therefore such energy saving devices preferably are used only when the reduced light output is acceptable or tolerable. U.S. Pat. Nos. 4,082,981 and 4,163,176 disclose devices attached to an end of a fluorescent lamp and containing a capacitor connected electrically in series with the lamp. These arrangements require the use of fluorescent bulbs shorter than standard, or fixtures longer than standard, so that the bulb and attached capacitor device will fit between sockets of the fixture. Another approach has been to insert a capacitor in the ballast circuit and in series with the lamp or lamps and the secondary winding of the ballast transformer, such as disclosed in U.S. Pat. Nos. 3,323,013; 3,911,320; 3,954,316; and 4,135,115. U.S. Pat. No. 3,956,665 discloses a "phantom" fluorescent lamp which does not produce light and which contains a capacitor connected between a terminal at each end, and is intended to replace one of the lamps of a two-lamp system.